RESUMO
Despite the economic and zoonotic relevance of caseous lymphadenitis, a competent immunoprophylaxis tool is still necessary. Here, we evaluated two putative virulence factors of Corynebacterium pseudotuberculosis, rNanH, and rPknG, as recombinant subunit vaccines in a murine model against the infection by C. pseudotuberculosis. Three groups of ten Balb/c mice each were inoculated with a sterile 0.9% saline solution (G1), rNanH (G2), or rPknG (G3) in formulations containing saponin as an adjuvant. The mice received two vaccine doses intercalated by a 21-day interval and were challenged with 2 × 104 CFU/mL of the C. pseudotuberculosis MIC-6 strain 21 days after the last immunization. The total IgG, IgG1, and IgG2a production levels increased significantly in the experimental groups (G2 and G3) on day 42. The highest levels of IgG2a antibodies in G2 and G3 were observed compared to IgG1 levels. G3 showed a significant (p < 0.05) humoral response through higher production of total IgG at day 42 when compared to G2. A significant increase of mRNA expression levels of interleukin (IL)-17, tumor necrosis factor, and interferon-γ was observed only in G2, while IL-4 was significantly produced only by G3. The levels of IL-10 and IL-12 obtained were not significant in any group. The survival rates after the challenge were 20% for G3 and 60% for G2 (p < 0.05). Our findings suggest that the formulation containing rNanH and saponin (G2) resulted in the best protection against the challenge and was able to elicit a Th1 immune response in mice, and can be considered as a promising antigen in the development of an effective vaccine against caseous lymphadenitis.
Assuntos
Infecções por Corynebacterium , Corynebacterium pseudotuberculosis , Linfadenite , Animais , Vacinas Bacterianas , Infecções por Corynebacterium/prevenção & controle , Corynebacterium pseudotuberculosis/genética , Linfadenite/prevenção & controle , Camundongos , Fatores de Virulência/genéticaRESUMO
The cattle tick Rhipicephalus(Boophilus) microplus is responsible for major losses in the Brazilian livestock, mainly due to reduction in cattle productive performance. Resistance development to major classes of acaricide widely used nowadays has been extensively reported, as well as the occurrence of residues from these compounds in animal products and the environment. This study aimed to evaluate the efficiency of acaricides onR. (B.)microplus collected from rural properties in the North-Central region of Bahia State. Ticks were collected in several cattle farms in the cited region, and an in vitro acaricide efficiency assay was performed based on the immersion of ticks in acaricide solutions made according to manufacturers' recommendations. The results obtained in the experiments indicated varying degrees of efficiency of the several bases studied, with the products benzofenilurea, macrocyclic lactone and fipronil showing the highest levels of efficiency, 100%, 100% and 97.34%, respectively. It was possible to conclude that, for the region studied, there are different degrees of commercial acaricides efficiency, and many present less than 95% effectiveness, value determined as acceptable by the Brazilian legislation.
O carrapato Rhipicephalus(Boophilus) microplusé responsável por grandes perdas na pecuária brasileira, principalmente devido à redução no desempenho produtivo dos animais. A resistência do parasita a diferentes classes de acaricidas tem sido amplamente relatada, bem como os problemas de ocorrência de resíduos desses compostos em produtos de origem animal e no ambiente. Esse estudo teve como objetivo avaliar a eficiência de diversos acaricidas sobre populações de R.(B.) microplus provenientes de propriedades rurais da Região Centro-Norte do Estado da Bahia, Brasil. Teleóginas ingurgitadas foram colhidas em diferentes propriedades da região e submetidas a ensaio in vitro de eficiência de acaricidas, baseado na imersão dos carrapatos em soluções de acaricidas feitas seguindo as recomendações dos fabricantes. Os resultados obtidos indicam níveis variados de eficiência das bases estudadas, com os acaricidas benzofenilureia, lactona macrocíclica e fipronil apresentando os índices mais altos de eficiência, 100%, 100% e 97.34%, respectivamente. Pode-se concluir que, para a região estudada, os acaricidas apresentam níveis diversos de eficiência, e muitos deles possuem eficácia de menos de 95%, como recomendado pela legislação brasileira.